Effects of rapid thermal annealing on optical properties of p-doped and undoped InAs/InGaAs dots-in-a-well structures

Postgrowth rapid thermal annealing was used to investigate the intermixing and structural changes in p-doped and undoped InAs/In0.1Ga0.9As dots-in-a-well (DWELL) structures grown by molecular beam epitaxy. Interdiffusion of In and Ga atoms caused by thermal annealing was proven from photoluminescence (PL) measurements, where blueshifts of the energy peaks were observed. The results show that p-doped quantum dot (QD) structures are more resistant to intermixing with higher thermal energy onset, and the reason is explained as the suppressed Ga diffusion resulted from the Be dopant. Rapid quenching of the integrated PL intensity at high temperature was observed in both undoped and p-doped DWELL QDs. Good agreement was obtained by fitting the integrated PL profile using two nonradiative recombination mechanisms, resulting in two activation energies that correspond to loss of carriers to nonradiative centers.